Best Practices for Managing Secrets in ECS Environment

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Hello, I am working with a customer who is concerned about the security of secrets within their ECS environment. Specifically, they are worried about secrets potentially leaking from containers and being accessed by downstream services like DataDog and others.

They are trying to decide the best way to securely manage and access secrets in ECS containers. Should they use environment variables, or is there a more secure alternative to ensure secrets are not exposed in this way?

Some of the team members have proposed exposing secrets as environment variables, but I’m concerned that this might be less secure than having the application read the secrets directly from a more controlled source. However, environment variables seem to be a common approach for many users, so I’m curious to hear about the pros and cons of each method.

Is it safer to let the application read secrets directly (e.g., from AWS Secrets Manager or SSM) at runtime? If environment variables are still the preferred approach, how can we mitigate the risk of secrets leaking to monitoring services or other downstream systems?

Would be helpful to get insights on best practices for securely managing secrets in ECS.

3 Answers
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When it comes to managing secrets in an Amazon ECS environment, there are several best practices to consider for ensuring the security of sensitive information.

First and foremost, it's highly recommended to use AWS Secrets Manager or Amazon EC2 Systems Manager Parameter Store for storing secret materials such as API keys, database credentials, and other sensitive information. These services provide secure, managed key-value stores that use AWS Key Management Service (KMS) for encryption, offering a robust foundation for secret management.

While exposing secrets as environment variables is a common approach, it does come with some security risks. Secrets stored as environment variables can potentially be exposed through various means, including logging, error messages, or access by unauthorized processes or services like monitoring tools.

A more secure alternative is to have the application read secrets directly from AWS Secrets Manager or Systems Manager Parameter Store at runtime. This approach offers several advantages:

  1. Better access control: You can use IAM roles and policies to tightly control which applications or services can access specific secrets.
  2. Reduced exposure: Secrets are not stored in the container environment, minimizing the risk of accidental exposure.
  3. Centralized management: Secrets can be easily rotated, audited, and managed from a central location.
  4. Dynamic updates: Applications can fetch the most up-to-date secrets without requiring container restarts.

To implement this approach, you would need to modify your application code to retrieve secrets directly from the secure store at runtime. This may require some additional development effort but provides a higher level of security.

If you must use environment variables due to application constraints or other reasons, there are ways to mitigate the risks:

  1. Use the secretOptions parameter in your ECS task definition to inject secrets as environment variables at runtime, rather than hardcoding them in your task definition or Dockerfile.
  2. Implement strict IAM policies to control which tasks can access which secrets.
  3. Regularly rotate secrets to limit the potential impact of exposure.
  4. Use encryption in transit to protect secrets as they're being injected into containers.
  5. Implement logging filters to prevent accidental logging of sensitive information.
  6. Configure your monitoring and observability tools to exclude or mask sensitive environment variables.

Regardless of the method chosen, it's crucial to follow the principle of least privilege, granting only the necessary permissions to specific IAM principals. Additionally, implement comprehensive logging and monitoring of your ECS environment to detect any unusual access patterns or potential security breaches.

In conclusion, while environment variables are widely used, having applications read secrets directly from AWS Secrets Manager or Systems Manager Parameter Store at runtime is generally considered a more secure approach for managing secrets in an ECS environment. This method provides better control, reduces exposure, and aligns with AWS best practices for secret management.
Sources
Best practices for secrets management in Amazon ECS - Amazon Elastic Container Service
Security considerations for running containers on Amazon ECS | AWS Security Blog
SEC02-BP03 Store and use secrets securely - AWS Well-Architected Framework
AWS Secrets Manager best practices - AWS Secrets Manager

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answered 2 months ago
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EXPERT
reviewed 2 months ago
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reviewed 2 months ago
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Hi,

AWS Secrets is clearly the way to go: https://aws.amazon.com/secrets-manager/

They have several advantages:

  • Your various security principals proper need IAM authorization to access them
  • Secrets are encrypted at rest using AWS KMS.
  • Secrets are never exposed in plaintext in the ECS task definitions or logs.
  • Automated secret rotation reduces the risk of stale secrets being used.

This Repo article may be useful: https://repost.aws/knowledge-center/ecs-data-security-container-task

You may want to read these articles for more details:

Best,

Didier

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answered 2 months ago
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reviewed 2 months ago
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I agree with Didier. I'd definitely recommend you to go with a AWS secrets manager because of a variety of benefits:

  1. Storage Options: Use Parameter Store for non-sensitive configurations (free but needs good naming convention), and Secrets Manager for sensitive data requiring encryption and rotation.

  2. Implementation Methods: Either use Task Definition's "secrets" section to set OS variables, or implement AWS SDK to pull secrets directly during container startup.

  3. Rotation Strategy: Consider that environment variables require container restart when rotated, while SDK implementation allows real-time updates without restart.

  4. Access Control: Implement proper IAM permissions for container access to secrets, and only use Secrets Manager for data requiring automatic rotation due to cost considerations.

Resources that I found useful other than one answer already. https://docs.aws.amazon.com/AmazonECS/latest/developerguide/secrets-envvar-secrets-manager.html https://docs.aws.amazon.com/AmazonECS/latest/developerguide/secrets-envvar-secrets-manager.html

answered 2 months ago

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